In the UK, around 9,000 cases of TB are reported each year, mainly in big cities like London

Source: World Health Organization/HPA

She told the BBC: "If you could predict which so-called carriers of TB will progress to the full-blown disease, this would have major ramifications for stopping the global epidemic.

"We just have to prove it now, but it's very promising."

Mike Mandelbaum, chief executive of the charity TB Alert, said good progress had been made in the diagnosis of latent TB infection in recent years, but there was a need for a specific test for the active disease.

The diagnosis of TB is often difficult to make until the disease has become infectious to others, he said, particularly in the developing world which has fewer resources.

"A new diagnostic technique based on a blood test would be extremely valuable to save lives and prevent the spread of this disease," he said, "and may be particularly important in HIV positive patients with TB where the usual technique of diagnosis from sputum is often unhelpful."

Dr Marc Lipman, chairman of the TB special advisory group at the British Thoracic Society, said it was "a remarkable piece of research".

He explained: "This for the first time perhaps enables us to start to design tests which can predict who is at highest risk of progressing to active disease and also how we might stop that occurring in the first place.